Push-button controls are often used to operate pneumatic, electrical or mechanical switches or valves. The switch or valve is usually contained in a switch housing, which is located behind a control panel. An externally mounted control button is pushed to activate the switch by moving a plunger that extends through an opening in the control panel and switch housing.
The opening through which the plunger moves provides a direct passageway from the exterior environment to the interior of the switch housing. Because such switches are often utilized in environments that are repeatedly subjected to moisture or chemicals, the opening must be sealed to exclude such contaminants from the switch housing interior. In the absence of a seal, moisture or chemicals may enter the housing and contact the switch mechanism, leading to corrosion and, eventually, failure of the switch.
Dental and medical facilities are exemplary of the kinds of harsh environments in which push-button switches are used. The sanitizing chemicals used in cleaning dental and medical equipment can contribute to rapid corrosion and switch failure if allowed to enter the switch housing and contact the switch mechanism. Since the equipment are sanitized on a regular basis, excluding sanitizers from the interior of the switch housing is critical to ensuring that the switch does not fail. Thus, the push-button control must comprise an assembly that seals the opening in the control panel and switch housing. In addition, the push-button control must be easy to actuate.
Another consideration in designing push-button controls for use in dental and medical applications is the elimination of locations where contaminants might accumulate. Thus, the push-button control and any associated sealing mechanism should be designed to minimize or eliminate crevices and grooves.
As a specific example, a cuspidor used in dentistry has a control panel that includes push-button-controlled switches or pneumatic valves to control the flow of water. Proper hygiene mandates regular sanitization of these control panels. To prevent corrosion of the switches by the sanitizing chemicals and water, it is important to seal the buttons. Thus, the externally located push-button must include a seal that is effective to exclude moisture, chemicals and other contaminants from the interior of the switch housing, yet facilitate easy actuation of the switch. In addition, the push-button/seal assembly should be free of crevices and grooves to eliminate locations for accumulation of contaminants.